Background: Primary percutaneous coronary intervention (PPCI) is the recommended treatment for acute ST-elevation myocardial infarction (STEMI). However, 40% of patients receiving initial PCI may experience the no-reflow phenomenon (NRP), which can enlarge the myocardial infarction region and increase death rate. Objectives: The aim of the current work was to ascertain the role of the mean platelet volume (MPV) and neutrophil-to-lymphocyte ratio in predicting coronary no-reflow in STEMI cases undergoing PPCI. Patients and Methods: This prospective study included a total of 100 patients with ST segment elevation myocardial infarction (STEMI) treated with primary PCI at Nasser Institute Hospital and Ain Shams University Hospitals. The patients were divided into 2 groups according to TIMI flow grades after primary PCI. 50 patients with TIMI flow grade 3 formed (reflow group) and 50 patients with TIMI flow grades 0-2 formed (no-reflow group). Results: Cases which manipulated with post stent dilatation in no-reflow group were significantly higher than in the reflow group (P = 0.028). Ejection fraction (EF) by M mode was significantly lower in the no-reflow group cases compared to those of reflow group (P = 0.040). Absolute lymphocytes were significantly higher in the no-reflow group cases compared to those of reflow group (P = 0.001). When compared to cases in the reflow group, the neutrophils to lymphocytes ratio was significantly higher in the no-reflow group cases (P = 0.011). When compared to the reflow group cases, MPV was significantly higher in the no-reflow group cases (P = 0.001). Hb level was significantly higher in the no-reflow group cases compared to those of reflow group (P = 0.005). Mean platelet volume and Neutrophil to lymphocyte ratio are considered a promising positive predictor of no-reflow phenomenon after primary PCI. Conclusion: It could be concluded that mean platelet volume is thought to be a potentially favorable predictor of the no-reflow phenomenon. New independent variables for forecasting no-reflow phenomenon in patients having PPCI include post-stent dilatation and EF by M mode. In patients having PPCI, the neutrophils to lymphocytes ratio plays a part in forecasting the no-reflow occurrence.